Conventional systems and methods for multi-tone modulation employ a signal constellation for each of a plurality of center frequencies in which each possible permutation of data elements, such as bits, is represented uniquely.
A multi-tone signal consists of data elements modulated onto each center frequency signal constellation. This modulation may be done on a per frequency basis, or may be done in parallel using IFFT technology for example
Disadvantageously, some permutations of constellation points for the frequencies will result in a high peak power in the multi-tone signal. Other permutations of constellation points for the frequencies will result in a low peak power in the multi-tone signal.
An example of this is shown in FIG. 1, where shown at 10 is a multi-carrier layout which may be used in OFDM for example. In this example, there are eight carriers. The amplitude of the multi-carrier signal results from complex addition of constellation points used for the multiple carriers. Most of the time, this complex addition will result in a value near some average value since the values being combined are typically somewhat random. An example of a somewhat random complex addition is given at 12 with the magnitude of the combination being indicated at 14.
In other cases, the complex addition will result in a large peak because the values all combine additively. An example of this is given at 16, where the magnitude of the combination is indicated at 18.
It would be advantageous to have a multi-carrier modulation method which did not suffer from these disadvantages.